Construction and operation of tunnel kilns



Oct. 6, 1925. w

R. w. STEERE CONSTRUCTION AND OPERATION OF TUNNEL KILNS Filed June 18,1920 K I. g i

Patented Oct. 6, 1925.

UNITED STATES PATENT orrlcn.

'RO'BERT W. STEERE, 0F PROVIDENCE, RHODE I SLAND,'AS'SIGNOR TO AMERICANDRESS- LER TUNNEL KIIiNS, INCL, OF NEW YORK, N. Y., A CORPORATION OF NEWYORK.

Application filed June 18, 1920. Serial- Ho. 390,012.

To all whom it may concern:

Be it known that I, ROBERT W. STEERE, citizen of the United States, andresident of Providence, in the county of Providence and State of RhodeIsland, have invented oer-- tain new and useful Improvements inGoristruction and Operation of Tunnel Kilns, of which the following is aspecification.

My present invention relates 'to continuous tunnel kilns and has to dowith the injection of solid material into the kiln chamber in a finelydivided foiq'm for the purpose of modifying the character, or at leastthe iappearance of the Ware passing through the (iln.

My invention was primarily devised for use in flashing brick in theirpassage through the tunnel kiln in which they are burned. Toaccomplish'this in accordance with the present invention I-dischargepowdered coal into the kiln chamber at a point wherein the brick are at,or near their maxi-.

mum temperature. To increase the surface coloration, or ratherdiscoloration produced by the powdered coal I may mix with the lattersome other substance such as chloride of sodium or potassium. Myinvention is applicable to various types of kilns and particularly bothto open fire and mufile kilns.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to v v and forminga part of this specification. For a better understanding of theinvention, however, and the advantages possessed by it reference shouldbe had to the accompanying drawings and descriptive matter in which Ihave illustrated and described some of the forms of apparatus by whichmy invention may be carried out.

Of the drawings;

Fig. 1 is a diagrammatic plan of an open fired tunnel kiln.

Fi 2 is a section taken on the line 2-2 of Fig. 1. Y

Fig. 3 is a diagrammatic elevation with parts broken away and in sectionof a muffle heated kiln.

Fig. 4 is a section on the line H of Fig. 3; and

Fig. 5 is a sectional elevation of the means employed alike in Figs. 1and 2, and Figs. 3 and 4t and for injecting solid material into the kilnchamber.

In Figs. 1 and 2 I have illustrated the ing zone of the kiln.

use of m invention in connection with an open fire kiln comprising anelongated kiln chamber A with an entrance door B at one end and an exitdoor B at the opposite end. The brick to be fired or other ware to beheated in the kiln are-carried through the latter on the usual cars Drunning on track rails C. At an intermediate portion of the kiln burnerchambers E are formed in the side walls of the kiln chamber. Thesereceive air through inlets F from air supply conduits F. As shown theair supply conduits F are supplied with heated airby means of fans orblowers G which draw the from which they pass through the outlet M to astackM which provides the necessary draft. I

Powdered coal, or a mixture of powdered deal with common salt or otherfinely divided solid material is discharged into the kiln chamberthrough inlets A in its side wall. These inlets open to the kiln chamberadjacent, but at the exit side of the burner chambers-F. The solidmaterial 'is passed to the inlets A through an ejector nozzle I intowhich an air blast nozzle J projects. The coal or othersolid material ispassed into each nozzle I through an inlet 1 from a hopper K to whichthe solid material is asse from a second hopper K at a reguated rate, asby means of a screw conve or K. It will be understood that the mec anismshown for passing the solid material into the kiln chamber through theinlets A is substantially like that employed for blowing powdered coalinto furnace chambers heated by the combustion of such fuel and that theparticular kind of apparatus shown in a somewhat diagrammatic manner forthisv purpose may be replaced by other known or suitable forms of aparatus. A damper controlled stack out et L opens chamber 'to theentrance end of the latter through the roof of the kiln chamber adjacentthe inlets A for withdrawing gases and vapors from this section of thekiln chamber. Instead of using a jet of air to carry the coal into thekiln chamber,- a jet of other fluid as a mixture of air and gas or steammay be employed.

In the contemplated mode of use of the apparatus shown in Figs. 1 and 2in flashing brick, the brick entering the kiln chamher past the door Bare moved gradually through the kiln chamber. As the br ck passes fromthe entrance end of the k1ln chamber to the portion of the latter atwhich the burner chambers are located, they are more or less graduallyheated up, and the brick are at practically their maximum temperaturewhen they pass into the zone of the kiln chamber receiving powderedmaterial through the inlets A. The powdered coal, or mixture of powderedcoal and salt, blown into the kiln chamber through the inlets A shouldbe thoroughly dispersed in the kiln chamber. For this purpose the inletsA' are flared, and the discharge end of the nozzle I is tapered, asshown, but other known or suitable expedients may be employed forcausing the dispersion of the solid particles carried into the kilnchamber. The air blast by which the solid material is carried into thekiln is preferably restricted in amountso that the coal particles willburn with a reducing flame. The burning particles of coal impinging onthe surfaces of the brick and entering the interstices in the surfacesof the brick which are ordinarily ve rou h I reduce brick constituentsat the surface of the brick and thus eflect some discoloration. Inaddition the ash constituents of the coal melt or produce molten slagwhich produces a further discoloration of the brick surface. Salt orother material mixed with the coal and vaporized by the heat in the kilnchamber also produces its appropriate color marking on the surfaces ofthe brick. Excess vapors or gases produced in the zone of the kilnchamber into which the powdered material is discharged, are withdrawnthrough the stack L, the suction effect of which may be regulated by thedamper L. V It will be understood that the invention can be used inconnection with other types of open fire tunnel kilns than the one moreor less conventionally illustrated in Figs. 1 and 2. The invention mayalso be used, with the special advantage in connection with muflleheated kilns, such as the kiln of the Dressler type illustrated by wayof example in Figs. 3 and 4. The kiln shown in Figs. 3 and 4 comprisesan elongated kiln chamber AA, having an ante chamber A at its entranceehd and an exit chamber A at its o posite end. Doors (not shown) areordinarily provided at each end of the kiln chamber. The brick or otherware to be treated in the kiln chamber AA are moved through the latteron cars" DA runnin on track rails C. Combustion chambers are provided inthe kiln chamber along an intermediate portion of the latter. Thesecombustion chambers rest on the masonry benches A at the sides of thetrack rails C. To the exit end of each combustion chamber is connected agroup of tubes N which run to the entrance end of the kiln chamber andare there connected to a corresponding header N The headers N areconnected, as by means of a tunnel N, to a suitable draft creatingdevice which, as shown, is a stack M. Gas or other fluid fuel issupplied to each combustion chamber adjacent its head end through one ormore burner inlets R, of which two are shown. Air to support thecombustion of this fuel is supplied to each combustion chamber throughbranches Q of conduits Q formed partly in the benches A and partly abovethe benches A. The conduits Q, receive air through the duct P which isshown as being supplied with air by a fan or blower PA. the latterreceiving air from a duct 0 The latter, in turn receives air fromheaders O to which are connected the air traversed pipes 0 runningthrough the cooling zone of the kiln. The air which may be drawn intothe pipe 0 from the atmosphere abstracts heat from the cooling zone ofthe kiln and is thereby heated while at the same time cooling the wareas the latter moves toward the exit end of the kiln.

Powdered coal or other solid material is introduced into the zone of thekiln chamber AA lying between the combustion chambers N and the coolingpipe headers O. The powdered fuel passes into the kiln chamber throughinlet openings A which are flared and are supplied with the powderedcoal or other solid material through nozzles I of apparatus shown asidentical with that employed in Figs. 1 and 2 for discharging solidmaterial into the kiln chamber A. Excess gases and vapors generated inthe kiln chamber by the combustion or heating of the solid materialinjected may be withd awn through a stack L as in the construction firstdescribed. Those skilled in the art.will understand that the inventionis useful in surface finishing various kinds of ceramic ware, and by theterm ceramic ware I mean to include all clay and shale products which,like brick or sewer pipe for example, are advantageously surfacefinished by flashing or salt glazing.

While in accordance with the provisions of the statutes I haveillustrated and described the best modes of carrying out my inventionnow known to me it will be apparent to those skilled in the art thatmany changes may be made in the form of the apto first raise the ware toa maximum temperature and then to cool the ware as the latter is movedthrough the kiln chamber from one end to the other, and injecting afinely divided solid material into a high temperature portion of thekiln chamber to thereby produce surface markings on the ware andrestricting the dispersion longitudinally of the kiln out of said hightemperature kiln portion of said solid material and the gases formedtherefrom".

2. The method of burning and surface finishing ceramic ware whichconsists in passing the Ware through an elongated kiln chamber of acontinuous tunnel kiln heated to first raise the ware to a maximumtemperature and then to cool the ware as the latter is moved through thekiln chamber from one end tothe other, which consists in injecting afinely divided solid combustible material into a high temperatureportion of the kiln chamber bymeans of a fluid jet, to thereby I roducesurface markings on the ware and restricting the dispersionlongitudinally of the kiln-out of said high tem perature-kilnportion ofsaid solid material and the gases formed therefrom.

a 3'. The combination in a continuous tunnel kiln comprising anelongated kiln chamber and means for heating said kiln chamber, of meansfor injecting into and dispersing in a high temperature portion ofothekiln chamber, a finely divided solidsmaterial and means for restrictingdispersion longitudi nally ofthe kiln out of said high temperature kilnportion of said solid material and the gases formed therefrom.

4. The combination -with the elongated kiln chamber of a continuoustunnel kiln, of means for blowing powdered coal into a portion of thekiln chamber intermediate its ends and means for restricting dispersionlongitudinally of the kiln out of said high temperature kiln portion ofsaid solid material and the gases formed'therefrom.

5. The combinationin a continuous tunnelkiln comprising an elongatedkiln chamber and muffle heating means therefor,.of means for injectingfinely divided solid material into and dispersing it in a hightemperature portion of the kiln chamber and means for restrictingdispersion longitudinally, of the kiln out of said high tem erature kilnportion of said solid material and the gases formed therefrom.

6. The combination in a continuous kiln,

of an elongated kiln chamber having a'vapor outlet from an intermediatehigh temperature portion of the kiln chamber and means for injectingfinely divided solid material into and dispersing'it in saidintermediate portion of said kiln chamber and means for restrictingdispersion longitudinally of the kiln out of said high temperature kilnportion of said solid material and the gases formed. therefrom.

7. An open fire tunnel kiln provided with a main stack or fan and alsohaving an auxiliary stack or fan independent thereof by which specialgases and vapors which have been introduced into the kiln for specialpurposes may be removed therefrom without resort being had to the meansfor inducing the main draft. Y

8. An open fire tunnel kiln provided with a main stack or fan andalsohaving an auxiliary stackor fan independent thereof acting on the firingzone of the kiln whereby special gases and vapors which have beenintroduced into the kiln for special purposes may be removed from thefiring zone without resort being hadto the means for inducing the lnaindraft before said gases or vapors have the opportunity ofcomingincontact with ware in other parts of the kiln. Sgned at 171 Madison Ave,in the county of ew York and State of New York this first day of June,A. D. 1920.

ROBERT W. STEERE.

